... Band:2402MHz-2479MHz 2,Transfer rate:250K wireless voice door phone for long distance 500m 1V31,2.4G ISM Public Frequency Band:2402MHz ... means no signal, loud "drops" tones, prompted no signal, ends CALL state. Signal received, began to sound a beep tone: A ... , beep tone stopped , enter the call state with the green light. C:Indoor monitor keep a long red light and ring when ...